Chronic venous disease - Part II: Proteolytic biomarkers in wound healing

Venous leg ulcers (VLU) are characterized by sustained proteolytic microenvironment impairing the healing process. Wound fluid (WF) reflect the biomolecular activities occurring within the wound area; however, it is unclear if WF from different healing phases have different proteolytic profiles and how VLU microenvironment affects the wound healing mechanisms. We investigated the proteolytic network of WF from distinct VLU phases, and in WF- and LPS-stimulated THP-1 monocytes treated with glycosaminoglycan sulodexide, a well known therapeutic approach for VLU healing. WF were collected from patients with VLU during inflammatory (Infl) and granulating (Gran) phases. WF and THP-1 supernatants were analyzed for nine matrix metalloproteinases (MMP) and four tissue inhibitors of metalloproteinases (TIMP) by multiplex immunoassays. Our results demonstrated that: 1) WF from Infl VLU contained significantly increased concentrations of MMP-2, MMP-9, MMP-12, TIMP-1, and TIMP-2 compared to Gran WF; 2) WF from Gran VLU showed significantly increased levels of MMP-1, MMP-7, MMP-13, and TIMP-4 compared to Infl WF; 3) LPS- and WF-stimulation of THP-1 cells significantly increased the expression of several MMP compared to untreated cells; 4) Sulodexide treatment of both LPS- and WF-stimulated THP-1 significantly down-regulated the release of several MMPs. Our study provides evidence-based medicine during treatment of patients with VLU. WF from Infl and Gran VLU have different MMP and TIMP signatures, consistent with their clinical state. The modulation of proteolytic pathways in wound microenvironment by glycosaminoglycan sulodexide, provide insights for translating research into clinical practice during VLU therapy.

Inflammation and compression: the state of art

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Glycosaminoglycan sulodexide modulates inflammatory pathways in chronic venous disease

Inflammation represents an important epiphenomenon in the etiopathogenesis of chronic venous disease, a worldwide debilitating condition affecting millions of subjects. The pathophysiology of chronic venous disease (CVD) is based on the hemodynamic abnormalities in conjunction to alterations in cellular and extracellular matrix biocompounds. The endothelial dysfunction results from early perturbation in the endothelium linked to glycocalyx injury and promoted by inflammatory cells and mediators (such as matrix metalloproteinases and interleukins), which lead to progressive dilation of the vein resulting in chronic venous insufficiency. Activated leukocytes during the inflammatory process release enzymes, free radicals, chemokines and inflammatory cytokines in the vessel microenvironment, which are responsible for the changes of the venous wall and venous valve, reflux and venous hypertension, and the development/progression of tissue destruction and skin changes. Sulodexide, a highly purified mixture of glycosaminoglycans composed by 80% fast moving heparin and 20% of dermatan sulphate, exhibits anti-thrombotic and profibrinolytic properties, restoring also the essential endothelial glycocalyx. Glycosaminoglycan sulodexide has been also characterized to reduce the release of inflammatory cytokines/chemokines and to inhibit the matrix metalloproteinases-related proteolytic cascades, counteracting endothelial dysfunctions. The pleiotropic effects of sulodexide set the basis for a very promising agent in treating the spectrum of CVD.

Pathophysiology of chronic venous disease

Chronic venous disease (CVD) is a debilitating condition with a prevalence between 60-70%. The disease pathophysiology is complex and involves genetic susceptibility and environmental factors, with individuals developing visible telengiectasias, reticular veins, and varicose veins. Patient with significant lower extremity symptoms have pain, dermal irritation, swelling, skin changes, and are at risk of developing debilitating venous ulceration. The signature of CVD is an increase in venous pressure referred to as venous hypertension. The various symptoms presenting in CVD and the clinical signs that are observed indicate that there is inflammation, secondary to venous hypertension, and it leads to a number of inflammatory pathways that become activated. The endothelium and glycocalyx via specialized receptors are critical at sensing changes in shear stress, and expression of adhesion molecules allows the activation of leukocytes leading to endothelial attachment, diapedisis, and transmigration into the venous wall/valves resulting in venous wall injury and inflammatory cells in the interstitial tissues. There is a complex of cytokines, chemokines, growth factors, proteases and proteinases, produced by activated leukocytes, that are expressed and unbalanced resulting in an environment of persistent inflammation with the clinical changes that are commonly seen, consisting of varicose veins to more advanced presentations of skin changes and venous ulceration. The structural integrity of protein and the extracellular matrix is altered, enhancing the progressive events of CVD. Work focusing on metabolic changes, miRNA regulation, inflammatory modulation and the glycocalyx will further our knowledge in the pathophysiology of CVD, and provide answers critical to treatment and prevention.

Development and use of sulodexide in vascular diseases: implications for treatment

Sulodexide (SDX), a sulfated polysaccharide complex extracted from porcine intestinal mucosa, is a blend of two glycosaminoglycan (GAG) entities, namely a fast-moving heparin (HP) fraction and a dermatan sulfate (DS; 20%) component. The compound is unique among HP-like substances in that it is biologically active by both the parenteral and oral routes. A main feature of the agent is to undergo extensive absorption by the vascular endothelium. For this reason, in preclinical studies, SDX administered parenterally displays an antithrombotic action similar to that of HPs but associated with fewer alterations of the blood clotting mechanisms and tests, thus being much less conducive to bleeding risk than HPs. When given orally, SDX is associated with minimal changes in classic coagulation tests, but maintains a number of important effects on the structure and function of endothelial cells (EC), and the intercellular matrix. These activities include prevention or restoration of the integrity and permeability of EC, counteraction versus chemical, toxic or metabolic EC injury, regulation of EC-blood cell interactions, inhibition of microvascular inflammatory and proliferative changes, and other similar effects, thus allowing oral SDX to be considered as an endothelial-protecting agent. The best available clinical evidence of the efficacy of SDX administered orally with or without an initial parenteral phase is the following: alleviation of symptoms in chronic venous disease and especially acceleration of healing of venous leg ulcers; prevention of cardiovascular events in survivors after acute myocardial infarction; marked improvement of intermittent claudication in patients with peripheral occlusive arterial disease; and abatement of proteinuria in patients with diabetic nephropathy that may contribute to the amelioration or stabilization of kidney function. Although further clinical trials are warranted, SDX is presently widely accepted in many countries as an effective and safe long-term, endothelial-protecting drug.

Understanding breast cancer stem cell heterogeneity: time to move on to a new research paradigm

Human breast cancer (BC) is one of the leading causes of death for women worldwide, and is characterized by a group of highly heterogeneous lesions. The morphological and biomolecular heterogeneity of BC cells, accompanied by dynamic plasticity of the BC microenvironment and the presence of stem-like cells, make tumor categorization an urgent and demanding task.The major limitations in BC research include the high flexibility rate of breast cancer stem cells (BCSCs) and the difficulty of their identification. Improved profiling methods and extensive characterization of BCSCs were recently presented in BMC Cancer, highlighting that the majority of BC cells had a luminal EpCAMhigh/CD49f+ phenotype, and identification of CD44high/CD24low subpopulation of cancer stem cells significantly improves the flow cytometry measurement of BCSCs with higher stem/progenitor ability.Future developments in single-cell omics will potentially revolutionize cancer biology and clinical practice, providing better understanding of BC heterogeneity, how BCSCs evolve, and which BC cells to target to avoid drug resistance.Please see related research published in BMC Cancer: http://www.biomedcentral.com/1471-2407/13/289/abstract.

Resolving breast cancer heterogeneity by searching reliable protein cancer biomarkers in the breast fluid secretome

BACKGROUND

One of the major goals in cancer research is to find and evaluate the early presence of biomarkers in human fluids and tissues. To resolve the complex cell heterogeneity of a tumor mass, it will be useful to characterize the intricate biomolecular composition of tumor microenvironment (the so called cancer secretome), validating secreted proteins as early biomarkers of cancer initiation and progression. This approach is not broadly applicable because of the paucity of well validated and FDA-approved biomarkers and because most of the candidate biomarkers are mainly organ-specific rather than tumor-specific. For these reasons, there is an urgent need to identify and validate a panel of biomarker combinations for early detection of human tumors. This is especially important for breast cancer, the cancer spread most worldwide among women. It is well known that patients with early diagnosed breast cancer live longer, require less extensive treatment and fare better than patients with more aggressive and/or advanced disease.

RESULTS

In the frame of searching breast cancer biomarkers (especially using nipple aspirate fluid mirroring breast microenvironment), studies have highlighted an optimal combination of well-known biomarkers: uPA + PAI-1 + TF. When individually investigated they did not show perfect accuracy in predicting the presence of breast cancer, whereas the triple combination has been demonstrated to be highly predictive of pre-cancer and/or cancerous conditions, approaching 97-100% accuracy.

CONCLUSION

Despite the heterogeneous composition of breast cancer and the difficulties to find specific breast cancer biomolecules, the noninvasive analysis of the nipple aspirate fluid secretome may significantly improve the discovery of promising biomarkers, helping also the differentiation among benign and invasive breast diseases, opening new frontiers in early oncoproteomics.

Deciphering the single-cell omic: innovative application for translational medicine

Traditional technologies to investigate system biology are limited by the detection of parameters resulting from the averages of large populations of cells, missing cells produced in small numbers, and attempting to uniform the heterogeneity. The advent of proteomics and genomics at a single-cell level has set the basis for an outstanding improvement in analytical technology and data acquisition. It has been well demonstrated that cellular heterogeneity is closely related to numerous stochastic transcriptional events leading to variations in patterns of expression among single genetically identical cells. The new-generation technology of single-cell analysis is able to better characterize a cell's population, identifying and differentiating outlier cells, in order to provide both a single-cell experiment and a corresponding bulk measurement, through the identification, quantification and characterization of all system biology aspects (genomics, transcriptomics, proteomics, metabolomics, degradomics and fluxomics). The movement of omics into single-cell analysis represents a significant and outstanding shift.

The matrix metalloproteinase inhibitor marimastat promotes neural progenitor cell differentiation into neurons by gelatinase-independent TIMP-2-dependent mechanisms

Metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs), produced in the brain by cells of non-neural and neural origin, including neural progenitors (NPs), are emerging as regulators of nervous system development and adult brain functions. In the present study, we explored whether MMP-2, MMP-9, and TIMP-2, abundantly produced in the brain, modulate NP developmental properties. We found that treatment of NPs, isolated from the murine fetal cerebral cortex or adult subventricular zone, with the clinically tested broad-spectrum MMP inhibitor Marimastat profoundly affected the NP differentiation fate. Marimastat treatment allowed for an enrichment of our cultures in neuronal cells, inducing NPs to generate higher percentage of neurons and a lower percentage of astrocytes, possibly affecting NP commitment. Consistently with its proneurogenic effect, Marimastat early downregulated the expression of Notch target genes, such as Hes1 and Hes5. MMP-2 and MMP-9 profiling on proliferating and differentiating NPs revealed that MMP-9 was not expressed under these conditions, whereas MMP-2 increased in the medium as pro-MMP-2 (72 kDa) during differentiation; its active form (62 kDa) was not detectable by gel zymography. MMP-2 silencing or administration of recombinant active MMP-2 demonstrated that MMP-2 does not affect NP neuronal differentiation, nor it is involved in the Marimastat proneurogenic effect. We also found that TIMP-2 is expressed in NPs and increases during late differentiation, mainly as a consequence of astrocyte generation. Endogenous TIMP-2 did not modulate NP neurogenic potential; however, the proneurogenic action of Marimastat was mediated by TIMP-2, as demonstrated by silencing experiments. In conclusion, our data exclude a major involvement of MMP-2 and MMP-9 in the regulation of basal NP differentiation, but highlight the ability of TIMP-2 to act as key effector of the proneurogenic response to an inducing stimulus such as Marimastat.

Nuclear localization of matrix metalloproteinases

Matrix metalloproteinases (MMPs) were originally identified as matrixin proteases that act in the extracellular matrix. Recent works have uncovered nontraditional roles for MMPs in the extracellular space as well as in the cytosol and nucleus. There is strong evidence that subspecialized and compartmentalized matrixins participate in many physiological and pathological cellular processes, in which they can act as both degradative and regulatory proteases. In this review, we discuss the transcriptional and translational control of matrixin expression, their regulation of intracellular sorting, and the structural basis of activation and inhibition. In particular, we highlight the emerging roles of various matrixin forms in diseases. The activity of matrix metalloproteinases is regulated at several levels, including enzyme activation, inhibition, complex formation and compartmentalization. Most MMPs are secreted and have their function in the extracellular environment. MMPs are also found inside cells, both in the nucleus, cytosol and organelles. The role of intracellular located MMPs is still poorly understood, although recent studies have unraveled some of their functions. The localization, activation and activity of MMPs are regulated by their interactions with other proteins, proteoglycan core proteins and / or their glycosaminoglycan chains, as well as other molecules. Complexes formed between MMPs and various molecules may also include interactions with noncatalytic sites. Such exosites are regions involved in substrate processing, localized outside the active site, and are potential binding sites of specific MMP inhibitors. Knowledge about regulation of MMP activity is essential for understanding various physiological processes and pathogenesis of diseases, as well as for the development of new MMP targeting drugs.

What does matrix metalloproteinase-1 expression in patients with breast cancer really tell us?

Molecular and biochemical expressions of matrix metalloproteinases in breast cancer tissue and cells offers promise in helping us understand the breast cancer microenvironment, and also in the future it is hoped this will improve its detection, treatment and prognosis. In a retrospective study recently published in BMC Cancer, microenvironment predisposing to breast cancer progression, metastatic behavior and the expression of matrix metalloproteinase-1 (MMP-1) and its correlation with well-known biochemical, molecular and clinicopathologic factors in breast cancer cells and cancer-associated stromal cells was examined; this study also analyzed patient survival in different breast cancer subtypes. The positive correlation in breast tumor and stromal cells between MMP-1 expression and several markers of tumor grade and stage provide us with some useful new insights into important questions about the molecular profiling of the stromal microenvironment in metastatic breast cancer. The study showed that MMP-1 expression is strongly associated with poor clinical outcome, so now we look forward to future larger studies in breast cancer patients in which we can relate wider MMP molecular profiling to identify lethal tumor and stromal microenvironments predisposing to breast cancer progression, metastatic behavior and poor prognosis. Please see related article http://www.biomedcentral.com/1471-2407/11/348.

Matrix metalloproteinase activity and glycosaminoglycans in chronic venous disease: the linkage among cell biology, pathology and translational research

Primary chronic venous disease (CVD) is an inflammatory pathology involving an erratic structural remodeling in the venous well leading to vascular incompetence and the development of varicose vein, characterized by altered collagen and elastin content. In the early steps of varicose vein formation is crucial the role of MMP/TIMP balance, implicated in both ECM and vascular degradation during inflammation processes in early and late stages of venous diseases. Although several pharmacological and surgical strategies are being utilized in the management of varicose vein and CVD with variable success and recurrence rate, inhibition of MMP through glycosaminoglycans may represent a novel therapeutic intervention to limit the progression of varicose vein to CVD and leg ulceration, suggesting possible opportunity to prevent future morbidity and enhancing clinical benefits and quality of life.